/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */
package org.apache.iotdb.db.mpp.plan.analyze;

import org.apache.iotdb.commons.path.PartialPath;
import org.apache.iotdb.commons.path.PathPatternTree;
import org.apache.iotdb.db.exception.sql.SemanticException;
import org.apache.iotdb.db.exception.sql.StatementAnalyzeException;
import org.apache.iotdb.db.mpp.plan.expression.Expression;
import org.apache.iotdb.db.mpp.plan.statement.Statement;
import org.apache.iotdb.db.mpp.plan.statement.component.ResultColumn;
import org.apache.iotdb.db.mpp.plan.statement.component.SelectComponent;
import org.apache.iotdb.db.mpp.plan.statement.crud.QueryStatement;

import java.util.ArrayList;
import java.util.List;
import java.util.stream.Collectors;

/**
 * This rewriter:
 *
 * <p>1. Concat prefix path in SELECT, WHERE, and WITHOUT NULL clause with the suffix path in the
 * FROM clause.
 *
 * <p>2. Construct a {@link PathPatternTree}.
 */
public class ConcatPathRewriter {

    private PathPatternTree patternTree;

    public Statement rewrite(Statement statement, PathPatternTree patternTree)
            throws StatementAnalyzeException {
        QueryStatement queryStatement = (QueryStatement) statement;
        this.patternTree = patternTree;

        // prefix paths in the FROM clause
        List<PartialPath> prefixPaths = queryStatement.getFromComponent().getPrefixPaths();

        if (queryStatement.isAlignByDevice()) {
            queryStatement.getSelectComponent().getResultColumns().stream()
                    .map(ResultColumn::getExpression)
                    .forEach(
                            expression ->
                                    ExpressionAnalyzer.constructPatternTreeFromExpression(
                                            expression, prefixPaths, patternTree));
        } else {
            // concat SELECT with FROM
            List<ResultColumn> resultColumns =
                    concatSelectWithFrom(
                            queryStatement.getSelectComponent(), prefixPaths, queryStatement.isGroupByLevel());
            queryStatement.getSelectComponent().setResultColumns(resultColumns);
        }

        // concat WHERE with FROM
        if (queryStatement.getWhereCondition() != null) {
            ExpressionAnalyzer.constructPatternTreeFromExpression(
                    queryStatement.getWhereCondition().getPredicate(), prefixPaths, patternTree);
        }

        // concat HAVING with FROM
        if (queryStatement.getHavingCondition() != null) {
            ExpressionAnalyzer.constructPatternTreeFromExpression(
                    queryStatement.getHavingCondition().getPredicate(), prefixPaths, patternTree);
        }

        return queryStatement;
    }

    /**
     * Concat the prefix path in the SELECT clause and the suffix path in the FROM clause into a full
     * path pattern. And construct pattern tree.
     */
    private List<ResultColumn> concatSelectWithFrom(
            SelectComponent selectComponent, List<PartialPath> prefixPaths, boolean isGroupByLevel)
            throws StatementAnalyzeException {
        // resultColumns after concat
        List<ResultColumn> resultColumns = new ArrayList<>();
        for (ResultColumn resultColumn : selectComponent.getResultColumns()) {
            boolean needAliasCheck = resultColumn.hasAlias() && !isGroupByLevel;
            List<Expression> resultExpressions =
                    ExpressionAnalyzer.concatExpressionWithSuffixPaths(
                            resultColumn.getExpression(), prefixPaths, patternTree);
            if (needAliasCheck && resultExpressions.size() > 1) {
                throw new SemanticException(
                        String.format(
                                "alias '%s' can only be matched with one time series", resultColumn.getAlias()));
            }
            resultColumns.addAll(
                    resultExpressions.stream()
                            .map(
                                    expression ->
                                            new ResultColumn(
                                                    expression, resultColumn.getAlias(), resultColumn.getColumnType()))
                            .collect(Collectors.toList()));
        }
        return resultColumns;
    }
}
